The target date funds have a $1000 minimum and are quite reasonable options for retirement or general diversified investments. The expense ratio is slightly higher, but if you have less than $3000, the difference is miniscule.

Or you can buy ETF versions of Vanguard funds. Same expenses as mutual fund versions, but the minimum purchase is 1 share. Free to trade from a Vanguard account (or something like this Schwab account, since its exchange traded).